The objective of this proposal is to study the role of prostaglandins in the regulation of utero-placental blood flow. The principal analytic method to be employed is the radioimmunoassay of prostaglandins A, E, and F. In addition new radioimmunoassays will be developed for the chief circulating metabolites of E and F prostaglandins. Physiological experiments will be performed on pregnant rhesus monkeys, measuring uterine blood flow, maternal blood pressure, prostaglandin, and prostaglandin metabolite levels. Experiments will be performed in awake, chronically catheterized animals. Studies will include the effect of prostaglandins, the effect of inhibitors of prostaglandin synthesis, and the response to hypoxia and ischemia.